The image of Richard Nixon waving his arms as he boarded a helicopter leaving the White house for the last time as president on August 9, 1974, remains etched in generational memories. The solemnness of Gerald and Betty Ford waving goodbye to the disgraced 37th president next to David Eisenhower consoling Julie Nixon was in direct contrast to the jubilation of millions celebrating his departure. No more Tricky Dick and the Pink Lady, Helen Gahagan Douglas, no more links to the un-American House Un-American Activities Committee, no more Watergate. Good riddance Milhouse, Pat, Roy Cohn, Bebe Rebozo, H.R. Haldeman and all that. Basta.

There are those moments like Nixon’s waving that define an era. Joseph N. Welch’s challenging Senator Joseph McCarthy during the Army-McCarthy hearings on June 9, 1954, was another such moment. Welch asked: “Have you no sense of decency, sir, at long last? Have you left no sense of decency?” he questioned the Wisconsin senator on national television. Welch pricked the balloon of McCarthy and his anti-Communist hearings. Welch’s simple questions captured all that was wrong with McCarthy and his hysterical witch hunt. Welch, a partner in the Boston white-shoe law firm Hale and Dorr, cut through the anti-Communist frenzy by questioning McCarthy’s “sense of decency.”

What do Nixon’s resignation and Welch’s questions have in common? Both represent unspoken norms. In the Welch case, the American people understood what decency meant. Although there was an exaggerated fear of Communists after World War II – Alger Hiss, Julius and Ethel Rosenberg – somehow Welch was able to capture a decency in the American people that began the closure of McCarthy’s prominence. McCarthy was not being decent, and he and his era started drawing to a close.

And Nixon? This is not as obvious. While those who defend Nixon point to his opening to China and end to the Vietnam War, his detractors will never get over his endless political intrigues. Was there ever a political figure progressives loathed more? One can easily trace the genealogy of dirty tricksters from McCarthy’s Roy Cohn (later a Nixon pal) directly through to Roger Stone, Lee Atwater and Roger Ailes, if not to Steve Bannon and Donald Trump. Nixon was their godfather.

What did Nixon do that he deserves to be fondly remembered? He resigned. In July 1974, the House Judiciary Committee approved three articles of impeachment against him: obstruction of justice, abuse of presidential powers, and hindrance of the impeachment process. On August 5, some transcripts of the Watergate recordings were released, including a segment in which the president was heard instructing Haldeman to order the FBI to halt the Watergate investigation. On August 8, Nixon announced he would resign, which he did the next day.

In an evening nationally televised address, Nixon said: “By taking this action, I hope that I will have hastened the start of the process of healing which is so desperately needed in America.” He threw in the towel before the full House impeached him; he resigned before formal Senate hearings could be held. Richard Nixon was never officially impeached or removed from office.

Rather than face impeachment by the full House of Representatives or trial by the Senate, Nixon left office, the first sitting United States president to do so. Would he have been removed from office by the Senate? Certainly, the Watergate tapes showed his direct orders to cover-up the Watergate break-in as well as evidence that several of his staff members were involved in the break-in.

If Welch was able to establish a sense of decency during the McCarthy era, Nixon must be given credit for resigning. He left office to hasten “the start of the process of healing which is so desperately needed in America.” We can easily say that he knew he would be found guilty and removed from office. But he left office before that could happen. In a sense, he acted decently.

Will Donald Trump leave office if Robert Mueller or the United States Attorney for the Southern District of New York recommend that the House charge him with high crimes or misdemeanors? Would Trump have the decency to step down as Nixon did? Trump said at a campaign stop in Iowa: “You know what else they say about my people? The polls, they say I have the most loyal people. Did you ever see that? Where I could stand in the middle of Fifth Avenue and shoot somebody and I wouldn’t lose any voters, okay? It’s like incredible.”

Incredible? No, indecent.

Will Trump have the decency to step down if there is enough evidence against him or have the norms of decency and healing become ancient history? If Republican senators begin moving away from him instead of merely following, and polls show weakening support for the president approaching the 2020 elections, will enough senators say to Trump that it is time he step down? Can we envision that? Can we envision Trump leaving in a helicopter waving to the crowd as Mike Pence takes over?

Fondly remembering Richard Nixon means we can hope it will happen again.